Variable trajectory kit for a ball pitching mechanism

ABSTRACT

The present invention is a method and apparatus for use with a ball throwing machine (e.g., baseball/softball pitching machines, tennis ball serving machines and the like) that may be employed for practice at hitting and/or catching balls thrown. In many conventional systems, such machines have a fixed position and are unable to vary the direction (horizontal) or angle (vertical) at which a ball is thrown. The present invention provides a simple, cost-effective device by which conventional machines may be adapted to provide randomly variable movement of the machine so as to enable a ball to move about a target location in order to simulate a competitive environment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 60/520,024, filed on Nov. 14, 2003 and U.S. Provisional Application Ser. No. 60/558,837, filed on Apr. 2, 2004, which are hereby incorporated by reference.

This invention relates generally to a throwing or pitching machine used in athletics for the practice of various ball dependant sports, such as baseball, football, tennis and the like, and more particularly to an improvement in the nature of a kit containing a mechanism to modify the trajectories of balls pitched or thrown by such machines.

BACKGROUND AND SUMMARY OF THE INVENTION

Pitching machines are powerful and versatile training tools for athletes of all ages and skill levels. Developing players benefit from the safety and predictability of a ball being repeatedly delivered within the center of the strike zone and thereby allowing the inexperienced athlete to work on swing mechanics under consistent conditions and thereby alleviate the fear of errant balls often thrown by the pitcher, coach, etc.

Pitching and throwing is often accomplished with one, or possibly two, driven wheels rotating in opposing direction that project the ball upon contact with the pair of counter-rotating radial surfaces which are co-acting to provide a curvilinear trajectory. Similarly, an arm of similar ball delivery mechanism may be employed to throw or project a ball toward a batter or receiver. Wheeled pitching machines mounted onto a tripod have been the industry standard for many years. Companies such at ATEC of Sparks, Nev., The Jugs Company of Tulatin, Oreg., and Bata Baseball Machines of San Marcos, Calif. have long marketed two wheeled pitching machines for use in a training environment. While these basic pitching machines are well suited for practicing the principle elements of a sport, they are all too often lacking in the ability to simulate actual game situations, such as high/low pitches and those that are to the inside or outside of the strike zone. Although described herein relative to a baseball pitching machine, it will be appreciated that the advantages of the present invention may be enjoyed in other ball sports and for purposes other than batting practice (e.g., infield and outfield practice, fly-ball practice, football receiver practice, etc. On one hand it is advantageous to consistently place the ball within a designated zone to perfect a technique, however this is an obvious contradiction to actual play where the trajectory and azimuth of the ball is relatively inconsistent and unpredictable. Admittedly, traditional pitching and throwing machines have a harmful effect in not providing the athlete the experience in reacting to balls that are randomly delivered within the peripheral border of the strike zone or the like, or even outside the strike zone all together.

In order to obtain the maximum advantage of conventional pitching machines there is an apparent need to provide a realistic batting session whereby the ball is delivered in a manner where the position of the ball, relative to the plate, is variable. This is a critical feature in providing experience in coordinating visual acuity with spontaneous muscle control and the development of gross motor skills. To that end pitching machines have now been developed whereby variations to the trajectory are applied in both the x and y directions using a variety of motion control methods and associated mechanics. Such devices are disclosed in U.S. Pat. No. 6,440,013, U.S. Pat. No. 6,440,013, U.S. Pat. No. 3,734,075 and U.S. Pat. No. 6,415,782. However, due to the complexity of the x and y movement mechanisms in such devices, there is no known retrofit kit providing for an “after market” integration of a variable trajectory feature into a conventional pitching machine mechanism.

Thus, there exists an unmet need to readily adapt existing pitching machines to accommodate the necessity for a more realistic training exercise by providing for a variable or randomized trajectory of the ball and relying on the batter to make an instantaneous decision as to the coordinates of the ball as it approaches the plate.

The present invention involves the adaptation of a ball pitching or throwing machine whereby a variable trajectory “kit” is operatively coupled to the pitching machine base for the purpose of continuously altering the trajectory of a pitch in order to provide a random presentation of the ball to the batter. The pitching machine as referenced in this invention comprises a ball tossing assembly affixed to a multi-leg base. The base may be a tripod, or other appropriate configuration that is capable of supporting and accommodating the re-coil of the pitching machine at a desired height and position.

Generally speaking the present invention is rotationally coupled to at least one leg, arm or corner of the supporting stand of a pitching machine. It will be appreciated, however, that as noted above the techniques described herein relative to the sport of baseball may be equally applied to other ball pitching devices and is therefore intended to include all those mechanical devices that are employed in the propulsion of game balls during training and practice sessions including, but not limited to, softball, hardball, tennis, badminton, football, ping-pong, lacrosse, and the like. In the preferred embodiment the invention acquires and controls at least one support member of the pitching machine and utilizes the member as a dynamic position control rod to oscillate the supporting structure of the pitching mechanism. The invention, in effect, intervenes between the supporting surface and a point of contact of at least one of the supporting legs to provide a fulcrum point as the trajectory of the propelled ball is continuously modified. Accordingly, this invention varies the vertical and/or horizontal vector of the ball with respect to the position of the batter or receiver where the resultant displacement within the strike zone, for instance, is the summation of the x (vertical) and y (horizontal) components where; y↑+x→=∠xy. It should also be appreciate that a relatively minor z component is inherent within the motion profile of the pitching machine due to the in/out displacement of the connection point between the pitching machine and the variable trajectory kit.

In accordance with a first aspect of the present invention, there is provided a means for producing a variable trajectory of the ball whereby the first direction of motion is continuously varied along with the second direction of motion. In effect this continuous adjustment of the x and y coordinates of the pitching machine facilitate an environment that emulates the throwing patterns of a pitcher. In actual practice this invention variably delivers the ball within a prescribed elliptical corridor contained within the “strike zone” by controlling both the horizontal and vertical orientation of the machine. A strike zone may be defined as a vertically orientated rectangular area over a home plate, where the width and horizontal position is relative to the home plate and the height and vertical position is relative to the batter.

In accordance with another aspect of the present invention, there is provided a free standing and autonomous displacement device for use in conjunction with a ball pitching machine, comprising a support base on the ball pitching machine; an eccentric drive operatively attached to said ball pitching machine, said drive generating displacement in at least a first direction using a single motor to produce a displacement of the ball pitching machine to alter the trajectory of a ball thrown therefrom and a means for adaptation to at least one leg of the multi-legged support, said adaptation means flexibly translating the motion from the drive means to the pitching machine.

In accordance with a further aspect of the present invention, there is provided a self-contained ball throwing machine comprising a means to throw a ball in a generally predetermined direction on a trajectory that is a function of the ball speed and angle of release; and an eccentric drive means associated with a motor and a control leg receiver operatively associated with at least one support of the ball throwing machine, wherein said control leg receiver is moved in at least one direction to effect a change in the direction or angle at which the ball is released so as to vary the location at which the ball is received in the vicinity of a target region, generally within a pre-defined strike zone, as a result of the variable displacement of the control leg receiver as the ball is released.

It is further intended that the present invention may be employed as an “after market” kit to enhance the functionality of existing pitching machines whereby the invention is readily installed and removed without the requirement for tools or modifications to the currently available pitching products. Furthermore, the drive means for varying the pitch trajectory is a single motor device having a minimum of moving parts, therefore being an economical and reliable improvement to a majority of the pitching machines currently in use. Moreover, the present invention accomplishes dual-direction variability of a pitching or throwing machine with only a single drive, thereby making the invention or “kit” easily transportable and attachable to multiple machines (e.g., may be used by the baseball coach one day and the tennis coach the next).

The integration of a variable trajectory drive system into a ball pitching or throwing machine is advantageous because this readily provides a complete range of ball orientations that are concurrent with actual playing conditions and can be presented to the batter or receiver with a minimal investment and modification to existing pitching devices. These and other objects and advantages of the present invention will become apparent to those skilled in the art after considering the following detailed specification, which describes an embodiment of the present invention in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention may be more easily understood from the following detailed description and by reference to the accompanying drawings in which:

FIG. 1 is a frontal view of the strike zone and the stance of the batter prepared to swing at a randomly pitched ball;

FIG. 2A is a perspective view of a a ball pitching device inserted into a receiving member of an eccentric drive assembly of “kit” in accordance with an embodiment of the present invention;

FIG. 2B is a front planar view of a roller assembly attached to another leg of the ball pitching device of FIG. 2A;

FIG. 3 is a perspective view of one embodiment of the eccentric drive assembly;

FIG. 4 is a perspective view of another embodiment of the motor and crank in the eccentric drive assembly;

FIG. 5 is a perspective view of another embodiment of the eccentric drive assembly incorporating a motor and cam;

FIG. 6 is a perspective view of another embodiment of the eccentric drive assembly incorporating a motor, cam and cam follower;

FIGS. 7-9 are views illustrating another embodiment of the eccentric drive assembly incorporating a cylinder having a helical and circumferential channel and a shroud with cam follower.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, in FIG. 1 the strike zone 28 is generally considered to be within an area immediately above home plate 33, where the upper limit thereof is a horizontal line at the midpoint between the top of the shoulders and the waist of batter 11, and the lower limit being a point extended from the knees of batter 11. Ball 40 is preferably presented within an elliptical pattern having both the minor and major axis within strike zone 28

Now in FIG. 2A a typical ball propelling machine 10, having a pair of variable speed pitching wheels 12, whereas the constructed and operated is well known within the art. The ball pitching machine 10 may comprise a variety of configurations capable of delivering a ball or similar projectile to a target including belts, a pneumatic cannon or an arm to impart a propelling force to ball 40. Machine 10, which is an embodiment designed to throw ball 40 at a variable speed, is generally supported by triangular base 15 forming a tripod whereby the machine 10 is moveably attached to the triangular base 15 by means of a coupling device 18. Coupling device 18 may accommodate horizontal and vertical adjustment of the trajectory of the ball 40. Once the flight of the ball 40 over the plate has been established the coupling device 18 is secured in position, for example using a thumb-screw or similar fastener threadably engaged within the coupling device 18, whereby the machine 10 is prohibited from moving off the pre-set pitch line, thereby providing a reliable and repeatable trajectory of the ball 40. The present invention employs an eccentric drive assembly 20 positioned underneath or adjacent to the existing triangular base 15 of machine 10. The eccentric drive 20 receives and controls at least one leg of the triangular base 15 and is constructed such that the machine 10 can be positioned and re-positioned to alter the trajectory of ball 40. The eccentric drive 20 therefore employs one of the supporting legs as a “tiller” or “arm” to steer the ball 40, preferably within the limits of strike zone 28.

As the eccentric drive 20 moves the control leg 16 up and down the angle or trajectory at which the ball is released, and similarly the height of the ball, 40 becomes variable. In like manner, as eccentric drive 20 concurrently moves the leg 16 left and right, the ball 40 will deviate from the nominal centerline accordingly. The motion output of eccentric drive 20 is intentionally asynchronous to the actual delivery or propulsion of the ball 40 from the machine 10 and thereby provides a multitude of trajectory angles for ball 40, as would be the case in an actual game. In order to assure even horizontal motion of the triangular base 15 at least one other leg may attached to a roller 21 (e.g., leg 19) or may be placed on a low friction skid pad 31 (e.g. leg 17) to enable movement about. However the movement of the other supporting legs may not be required if only unilateral vertical motion of the triangular base 15 is desired. Skid pad 31 may a sheet of material having a low coefficient of friction, such as PTFE, which is inserted beneath leg 17 to promote unrestrained horizontal motion of the point of contact to the ground or floor. Accordingly support leg 19, by remaining stationary, could provide a fulcrum for bi-lateral variable trajectory system. In an alternative embodiment at least one leg has attached a roller 21 whereby a stepped diameter adapter 23 is inserted within the leg 19 and axel 25 rotatably couples at least one wheel 27 to adapter 23 as depicted in FIG. 2B.

As described herein, a preferred embodiment of the present invention as shown in FIG. 3 is directed toward a high torque motor 22 having a relatively low angular velocity within a range of at least 1-30 rotations per minute (RPM) and preferably comprises an electric motor, with either AC or DC as a current source, or any other suitable power generating method capable of rotating a shaft. One such motor is an AC motor drive, Model 3805 from Multi-Products, Inc. having an output of 4 RPM. Crank 32 is eccentrically connected to the output shaft of motor 22 and provides for motion in the first plane when eccentric drive 20 is positioned to be generally perpendicular with control leg 16. In FIG. 2A eccentric drive 20 is shown as being in line with control leg 16 and accordingly moving the leg 23 of machine 10 in an elliptical pattern. In one embodiment, crank 32 may be attached to the output shaft of motor 22 having coupler 29 inserted in one of a plurality of positions along crank 32. By increasing the distance of coupler 29 from the motor shaft, and thereby increasing the displacement of control leg 16, a greater eccentric motion will be imparted on the machine 10 and accordingly an expanded projection pattern range will be achieved. Motor 22 is secured to mounting plate 24 that in turn rests on the ground or other common surface that is also supporting machine 10. Notably, eccentric drive 20 and roller 21 are readily attached to a plurality of pitching machines using one or more stepped adapters 23. As noted in FIG. 4, adapter 23 consists of a plurality of increasingly larger outside diameters to accommodate a range of support legs 16 having a corresponding or slightly larger inside diameter. Adapter 23 may also be constructed as a spherical cone, having an infinitely variable diameter from a minimum (point) to a maximum diameter. In the case of leg 16 being a solid rod, adapter 23 would further consist of a corresponding bore having an inside diameter to receive leg 16 therewithin. The aforementioned adapter 23 combined with a autonomous eccentric drive 20 allows for an efficient means to integrate or operatively couple a variable trajectory feature within the existing pitching machine population with the installation of this after market kit. It is to be noted that the adapter 23 does not have to be permanently or releasably fastened to the leg 16, but may be so fastened using any of a number of techniques such as locking screws, pins, etc.

FIG. 4 further depicts the details of the rotational coupling means comprising; crank 32, coupler 29, stepped adapter 23 and leg 16. Crank 32 may be attached to the motor shaft using a “D” shaped hole to correspond with a similarly shaped shaft, or it may be secured with a keyhole clamp formed within crank 32 and cinched with screw 14. It is appreciated by those skilled in the art that numerous alternatives are available to secure crank 32 to a D-shaped or cylindrical shaft including, but not limited to, a setscrew, dowel or roll pin, spline, threaded shaft with nut, keyway or welding to name a few. Bearing 13 is pressed into crank 32 to allow coupler 29 to freely turn within crank 32. Preferably adapter 23 moves in unison with coupler 29 having minimal relative motion as they interact due to the weight of pitching machine 10 and the corresponding force onto the socket of adapter 23 on the distal end of leg 16. It is anticipated that the ball and socket means is preferred to a permanent affixing or conjoining mechanism to connect adapter 23 to coupler 29 so as to provide a simplistic means for fitting eccentric drive 20 to control leg 16. However, in the case where the recoil force of pitching machine 10 may disrupt the connection a universal joint or similar means may be employed and attached to the leg 16 as noted above.

In an alternative embodiment as shown in FIG. 5, motor 20 may be attached by way of one or more slides or rails 26 to chassis 24. Cam 34 communicates directly to chassis 24 providing a force against a low friction surface or rollers 36 that, when rotated, displaces the mounting plate 51 and motor 22 attached thereto a distance equal to the offset of cam 34—thereby generating various deflections of the leg heights. As will be appreciated, the embodiment of FIG. 5 may be employed in a single-direction displacement (vertical) as well as a multi-direction displacement (vertical and horizontal) device. Attached to the eccentrically mounted cam 34, in common with cam 34 at the point of rotation, is control leg receiver 30, wherein a supporting leg of pitching machine 10 is operatively engaged as described above relative to FIG. 4.

Referring also to FIG. 6, the chassis 24 is now slideably interconnected to base plate 38. Guides 26 passes within respective vertical bores of the mounting plate 51 and are secured to chassis 24 thereby maintaining the mounting plate 51 in a stationary horizontal position but allowing vertical displacement. Cam 34 is eccentrically connected to the output shaft of motor 22. The offset of cam 34 is directly proportional to the minimum and maximum height of the pitched ball whereby the eccentric motion of cam 34 is coupled to the control leg 16 by means of control leg receiver 30. Receiver 30 is rotationally mounted to the output shaft of motor 22 having cam 34 positioned therebetween. Receiver 30 is configured to accept a plurality of leg form factors and is readily adapted to accommodate a variety of ball pitching machines 10. In this bi-directional embodiment the motor 22 and the mount plate 51 are allowed to move in a vertical manner along the path of the guides 26 as chassis 24 moves horizontally from a reactive force developed from roller 36 as the eccentrically driven cam 34 translates the rotary motion supplied by motor 22 into a single directional component that is concentric with the receiver 30. FIG. 5 best shows this embodiment whereby the motor 22, mounting plate 51 and receiver 30 all move in unison. While this arrangement unto itself is not specifically advantageous in developing reciprocating motion, it will become readily apparent from the following description as to the inherent advantages of this approach.

In particular, FIG. 6 shows a means to control the displacement of the pitching machine leg 16, and thereby a ball 40, in the horizontal plane concurrently with the motion in the vertical plane. Using the same motor 22 as a driving means, motion in the second plane is directly derived from the first plane motion whereby slide follower 43 mounted on the distal end of the motor 22 output shaft allows the motor 22 to move along the second plane as a function of, and concurrently with, the first plane motion. This composite displacement (two-directions—horizontal and vertical) is developed from first and second planes of motion substantially perpendicular to one another. Eccentric drive 20, as depicted in FIG. 5 has been adapted to develop motion in a second direction that is perpendicular to the first. With reference to FIG. 6 chassis 24 is positioned onto the upper surface of base plate 38. A pair of pins 47 operating within apertures 41, align chassis 24 to the fixed base plate 38 in a consistent orientation, whereas there is relative motion between the two base plates that is parallel to the drive shaft of motor 22. As shown in FIG. 6 slide deflector 42 is attached directly to base plate 38. The distal end of the output shaft of motor 22 extends into and beyond the curvilinear aperture within the slide deflector 42. Attached thereon to the end of the motor shaft, in direct contact with the outer surface of slide deflector 42, is slide follower 43. As shown in FIG. 6 the radial profile of slide deflector 42 is a function of the desired horizontal displacement of the pitched ball. As motor 22 moves along an axis perpendicular to the base plate a reactive right angle force is applied to receiver 30 through slide deflector 42, slide follower 43 and the motor shaft. The resultant motion as seen at control leg receiver 30 is the summation of the x (vertical) and y (horizontal) components of displacement where; y↑+x→=∠z. As will be appreciated, various slide deflector profiles may be employed, possibly substituted with one another, to achieve varying deflections patterns of the ball pitching apparatus.

In yet another embodiment, depicted in FIGS. 7-9, in order facilitate the random trajectory of a ball pitching machine as in FIG. 2, the eccentric drive 20 is positioned between a supporting surface and control leg 16 such as previously described, however the motion is generated using a cylinder in lieu of the aforementioned crank 32 or cam 34. With reference to FIGS. 7, 8 and 9 in general terms, there is provided an alternative means to develop motion or displacement in both the first and second plane using a single motor 22 directly affixed to base plate 38. A cylinder 52 having a uniform cylindrical surface is eccentrically attached to the output shaft of the motor 22. The surface of the cylinder contains one or more channels 54, 56 circumventing the cylinder. The radial channel 56 follows a linear path that is perpendicular to the axis of cylinder 52. Channel 54 is a helix that can be characterized as a continuous curve circumventing the diameter of the cylinder to form an elliptical or other motion profile. The shroud 58 has a cam follower or similar provisions for attaching between the cylinder and a leg of the triangular base 15 of pitching machine 10, and thereby transmitting to machine 10 the motion generated by the rotation of eccentrically mounted cylinder 52. In the case whereby only the height of the ball is to be controlled the cam follower is engaged in the radial channel 56 to constrain the attached shroud to the first plane of motion only. In the second case whereby the motion of the first plane is to be combined with motion in the second plane the cam follower or tracking pin 62 engages the helical channel 54, or a similarly configured varying-direction channel, thereby generating a composite angle of trajectory representing the sum of the first and second planes of motion. This multi-plane displacement pattern is directed to the pitching machine through the control leg 16 of the plurality of supporting legs of triangular base 15.

Referring now to FIG. 7, motor 22 is directly mounted to bracket 50. Cylinder 52 is attached to motor 22 at one of a plurality of possible mounting positions or points that are displaced from the geometric axis of cylinder 52. Cylinder 52 rotates in an eccentric manner whereby the offset distance between the motor 22 shaft and the centerline of the cylinder 52 is selected from a group of mounting holes corresponding to strokes that are proportional to the desired angle/height of the ball being pitched. Shroud 58, having a radius nearly equal to the radius of the cylinder 52, surrounds cylinder 52 in order to trace the motion created by the rotating cylinder, thereby generating a variable trajectory angle to manipulate the ball position across the plate. Control leg receiver 30, with adapter 48, is connected to control leg 16 of ball pitching machine 10, as previously described with respect to the embodiment of FIG. 2.

As shown in FIGS. 7, 8, and 9, the eccentrically driven cylinder 52 is rotated so shroud 58 oscillates the control leg receiver 30. The variation of only the height of the pitch is accomplished when tracking pin 62 and shroud 58, shown in FIG. 8, are engaged in channel 56 only of cylinder 52. Referring to FIG. 7, the horizontal displacement of the ball is determined by the offset of cylinder 52. A composite variation of the trajectory of ball 40 path is established when tracking pin 62 is engaged in channel 54 within cylinder 52. In this configuration both the x and y components are developed and applied to the control leg 16.

It will be appreciated that the above embodiments, while described within the context of the sport of baseball, are not limited or dedicated to any specific sport. On the contrary any athlete deriving training from a ball-propelling device will fully appreciate the features and benefits of the present invention.

Thus there has been described herein a ball pitching machine whereby the trajectory of the ball is randomly altered. It will be apparent to those skilled in the art that various changes may be made in the size, shape and arrangement of elements described hereinbefore without departing from the intended spirit, functionality and operability of the subject invention. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. 

1. A displacement device for a ball pitching machine, comprising: a support base on the ball pitching machine; an eccentric drive operatively attached to said ball pitching machine, said drive generating displacement in at least a first plane using a single motor to produce a displacement of the ball pitching machine to alter the trajectory of a ball thrown therefrom.
 2. The displacement device of claim 1, further comprising means, connected to the eccentric drive, for adapting and operatively coupling the eccentric drive to at least one leg of a multi-legged support for the pitching machine, wherein said means translates motion from the eccentric drive to the leg.
 3. The device of claim 1 wherein the eccentric drive further comprises a motor and a crank coupled to said motor, and where the adaptation means rotationally constrains at least an end of the control leg and causes said end of the control leg to move in at least two directions.
 4. The device of claim 1, wherein said device is position relative to the pitching machine so as to cause motion in three directions.
 5. The device of claim 1 wherein said leg adaptation means is engaged with at least one of the supporting legs of said ball pitching machine.
 6. The device of claim 1 wherein at least one other of said supporting legs includes at least one roller in contact with the supporting surface so as to enable at least one other of said supporting legs to move relative to the supporting surface.
 7. The device of claim 1 wherein at least one other of said supporting legs includes means for enabling sliding contact with the supporting surface.
 8. The device of claim 1 wherein said variable trajectory means is a crank having a plurality of holes therethrough and wherein one of said holes operatively receives the leg adaptation means.
 9. The device of claim 8 wherein said crank is affixed to a rotation means through one of said plurality of holes and the trajectory displacement is a function of the hole selected.
 10. A free standing ball throwing machine comprising: means to throw a ball in a generally predetermined direction on a trajectory that is a function of the ball speed and angle of release; and an eccentric drive means associated with a motor and a control leg receiver operatively associated with at least one support of the ball throwing machine, wherein said control leg receiver is moved in at least one direction to effect a change in the direction or angle at which the ball is released so as to vary the location at which the ball is received in the vicinity of a target region as a result of the variable displacement of the control leg receiver as the ball is released.
 11. A device for altering the position of a ball delivery machine having a plurality of legs to support the ball delivery machine on a surface, comprising: a leg mount to operatively connect the device to at least one of the legs; a crank; a pivotable connection between the leg mount and the cam, operatively coupling the leg mount to the cam; and means for rotating the crank about an eccentric axis, wherein the leg mount moves in at least a varying bi-directional manner as a rotating means is operated so as to cause the ball delivery machine to alter an angle at which a ball is delivered.
 12. The device of claim 11, wherein the leg mount receives a leg.
 13. The device of claim 11, wherein the leg is inserted, at least partially, into the leg mount.
 14. The device of claim 11, wherein rotating means is an electric motor.
 15. The device of claim 11, further including a roller operatively associated with at least one other leg. 